JPH04135355A - Doorphone slave unit - Google Patents
Doorphone slave unitInfo
- Publication number
- JPH04135355A JPH04135355A JP25999190A JP25999190A JPH04135355A JP H04135355 A JPH04135355 A JP H04135355A JP 25999190 A JP25999190 A JP 25999190A JP 25999190 A JP25999190 A JP 25999190A JP H04135355 A JPH04135355 A JP H04135355A
- Authority
- JP
- Japan
- Prior art keywords
- output
- circuit
- amplification factor
- receiver
- amplifier circuit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 230000003321 amplification Effects 0.000 claims abstract description 28
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 28
- 238000001514 detection method Methods 0.000 claims abstract description 11
- 230000005236 sound signal Effects 0.000 claims description 13
- 230000005540 biological transmission Effects 0.000 abstract description 6
- 238000010586 diagram Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 3
- 230000002265 prevention Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
Landscapes
- Interconnected Communication Systems, Intercoms, And Interphones (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、ハウリング防止機能を付加したドアホン子器
に関する。DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a door intercom slave unit with an additional howling prevention function.
第３図は、ドアホン子器１と親機装置２の外観を示す図
であり、一般に、ドアホン子器１は家屋の玄関先に設置
され、親機装置２は家屋内の居間等に設置され、ドアポ
ン子器１と親機装置２は電線路Ｗ、、Ｗ２で接続される
。FIG. 3 is a diagram showing the appearance of the doorphone slave unit 1 and the base unit device 2. Generally, the doorphone slave unit 1 is installed at the entrance of a house, and the base unit unit 2 is installed in the living room, etc. of the house. , the door-phone slave device 1 and the master device 2 are connected by electric lines W, , W2.
ドアホン子器１は少なくとも送話器に相当するマイクＭ
１と受話器に相当するスピーカーＲ１を備えると共に、
来訪者が住人に対して来訪したことを知らせるための押
釦スイッチ３１等を備えている。また、親機装置２は少
なくとも送話器に相当するマイクＭ２と受話器に相当す
るスピーカーＲ２を備えると共に、来訪者が住人に対し
て来訪したことを知らせるためドアホン子器１の押釦ス
イッチＳ１を押したとき報知音を鳴動する音響部０□や
、高級な親機装置２になると家屋内の防災防犯等のセキ
ュリティー機能をも備えている。The doorbell slave unit 1 has at least a microphone M corresponding to a transmitter.
1 and a speaker R1 corresponding to a receiver,
It is equipped with a push button switch 31 and the like for informing residents that a visitor has visited. The base device 2 is equipped with at least a microphone M2 corresponding to a transmitter and a speaker R2 corresponding to a receiver, and the visitor presses the push button switch S1 of the door intercom slave unit 1 to notify the resident of his/her visit. The sound part 0□ generates an alarm when an accident occurs, and the high-grade base unit 2 also has security functions such as disaster prevention and crime prevention inside the house.
従って、来訪者がドアホン子器１の押釦スイッチＳ１を
押すと、親機装Ｗ２の音響部０□は住人に対して来訪者
があることの報知音を鳴動する。Therefore, when a visitor presses the pushbutton switch S1 of the intercom slave device 1, the sound part 0□ of the main unit W2 sounds a sound notifying the resident that there is a visitor.
報知音で来訪者があることを知った住人は、親機装置２
のハンドセット３を取ってハンドセット３のマイクＭ２
およびスピーカーＲ２を介して玄関先の来訪者に話しか
けることができ、来訪者はドアホン子器１のマイクＭ１
およびスピーカーＲ１を介して住人に話しかけることが
できる。Residents who learned of the presence of visitors from the notification sound should turn on the base device 2.
Take handset 3 and insert microphone M2 of handset 3.
and speaker R2, the visitor can talk to the visitor at the front door, and the visitor can talk to the visitor using the microphone M1 of the doorphone slave device 1.
and can talk to residents via speaker R1.
第２図は従来のドアホン子器１および親機装置２の通話
回路の要部を示す回路ブロック図であり、ドアホン子器
１は電線路接続端子Ｔ１と電線路接続アース端子Ｔ３を
有し、また、親機装置２ば電線路接続端子Ｔ２と電線路
接続アース端子Ｔ。FIG. 2 is a circuit block diagram showing the main parts of the communication circuit of the conventional door intercom slave unit 1 and base device 2, and the door intercom slave unit 1 has an electric line connection terminal T1 and an electric line connection ground terminal T3, Moreover, the main device 2 has a power line connection terminal T2 and a power line connection ground terminal T.
を有している。ドアホン子器１の電線路接続端子Ｔ１と
親機装置２の電線路接続端子Ｔ２は電線路Ｗ１を介して
接続され、ドアホン子器１の電線路接続アース端子Ｔ３
と親機装置２の電線路接続アース端子Ｔ４は電線路Ｗ２
を介して接続されていドアホン子器１の内部回路では、
マイクＭ１の出力は送話増幅回路Ｅ１に接続され、送話
増幅回路Ｅ１の出力は略５ＭＨｚの周波数で音声信号を
変調する変調回路Ｆ、に接続され、変調回路Ｆ、の出力
は電線路接続端子Ｔ１に接続される。また、スピーカー
Ｒ１は受話増幅回路Ａ、の出力と接続され、受話増幅回
Ｆ！Ｍ Ａ ＋ は復調回路Ｂ、の出力と接続され、復
調回路Ｂ１は略６ＭＨｚを中心周波数とした帯域フィル
タ回路Ｃ１の出力と接続され、帯域フィルタ回路Ｃ１の
入力は電線路接続端子Ｔ１に接続される。have. The electric line connecting terminal T1 of the door intercom slave device 1 and the electric line connecting terminal T2 of the main device 2 are connected via the electric line W1, and the electric line connecting terminal T3 of the door intercom slave device 1 is connected to the electric line connecting terminal T2 of the main device 2.
and the electric line connection ground terminal T4 of the main unit device 2 is connected to the electric line W2.
In the internal circuit of door intercom slave unit 1, which is connected via
The output of the microphone M1 is connected to a transmitting amplifier circuit E1, the output of the transmitting amplifier circuit E1 is connected to a modulating circuit F that modulates the audio signal at a frequency of approximately 5 MHz, and the output of the modulating circuit F is connected to a power line. Connected to terminal T1. Further, the speaker R1 is connected to the output of the receiving amplifying circuit A, and the receiving amplifying circuit F! M A + is connected to the output of a demodulation circuit B, the demodulation circuit B1 is connected to the output of a bandpass filter circuit C1 whose center frequency is approximately 6 MHz, and the input of the bandpass filter circuit C1 is connected to the electric line connection terminal T1. Ru.
親機装置２の内部回路では、マイクＭ２の出力は送話増
幅回路Ｅ２に接続され、送話増幅回路Ｅ２の出力は略６
ＭＨｚの周波数で音声信号を変調する変調回路Ｆ２に接
続され、変調回ＢＦ２の出力は電線路接続端子Ｔ２に接
続される。また、スピーカーＲ２は受話増幅回路Ａ２の
出力と接続され、受話増幅回路Ａ２は復調回路Ｂ２の出
力と接続され、復調回路Ｂ２は略５Ｍ１ｆｚを中心周波
数とした帯域フィルタ回路Ｃ２の出力と接続され、帯域
フィルタ回路Ｃ２の入力は電線路接続端子Ｔ２に接続さ
れる。In the internal circuit of the base device 2, the output of the microphone M2 is connected to the transmitting amplifier circuit E2, and the output of the transmitting amplifier circuit E2 is approximately 6.
It is connected to a modulation circuit F2 that modulates an audio signal at a frequency of MHz, and the output of the modulation circuit BF2 is connected to an electric line connection terminal T2. Further, the speaker R2 is connected to the output of the receiving amplifier circuit A2, the receiving amplifier circuit A2 is connected to the output of the demodulating circuit B2, and the demodulating circuit B2 is connected to the output of the bandpass filter circuit C2 having a center frequency of approximately 5M1fz, The input of the bandpass filter circuit C2 is connected to the electric line connection terminal T2.
従って、従来のドアホン子器１と親機装置２の通話は次
のように行われる。Therefore, a conventional telephone conversation between the door intercom subunit 1 and the base unit 2 is performed as follows.
来訪者の音声はマイクＭ１からピックアップされ音声信
号として送話増幅回路Ｅ１へ出力される。送話増幅回路
Ｅ、からの増幅された音声信号は、略５ＭＨｚの周波数
で音声信号を変調する変調回路Ｆ、で変調され電線路接
続端子Ｔ１へ出力される。The visitor's voice is picked up from the microphone M1 and output as a voice signal to the transmission amplification circuit E1. The amplified audio signal from the transmitting amplifier circuit E is modulated by a modulation circuit F that modulates the audio signal at a frequency of about 5 MHz, and is output to the electric line connection terminal T1.
従って、電線路Ｗ、を介して接続された親機装Ｍ２の電
線路接続端子Ｔ２には、略５ＭＨｚの周波数で来訪者の
音声信号を変調する変調回路Ｆ１で変調された変調信号
が入力され、帯域フィルタ回路Ｃ２の入力となる。帯域
フィルタ回路Ｃ２は略５ＭＨｚを中心周波数としている
ので、帯域フィルタ回路Ｃ２はドアホン子器ｌのマイク
Ｍ１からピックアップされた来訪者の音声信号を変調し
た変調回路Ｆ１の出力のみ弁別して復調回路Ｂ２に出力
する。復調回路Ｂ２はドアホン子器１のマイクＭ１から
ピックアップされた来訪者の音声信号に復調して受話増
幅回ＦＩＢＡ２に出力し、受話増幅回ＢＡ２はスピーカ
ーＲ２を駆動する。そして、住人はスピーカーＲ２から
来訪者の音声を聴くことができる。Therefore, the modulation signal modulated by the modulation circuit F1 that modulates the visitor's audio signal at a frequency of approximately 5 MHz is input to the power line connection terminal T2 of the main equipment M2 connected via the power line W. , becomes the input of the bandpass filter circuit C2. Since the bandpass filter circuit C2 has a center frequency of approximately 5 MHz, the bandpass filter circuit C2 discriminates only the output of the modulation circuit F1 that modulated the visitor's voice signal picked up from the microphone M1 of the intercom slave unit L, and sends it to the demodulation circuit B2. Output. The demodulation circuit B2 demodulates the visitor's voice signal picked up from the microphone M1 of the door intercom slave unit 1 and outputs it to the reception amplification circuit FIBA2, and the reception amplification circuit BA2 drives the speaker R2. Then, the residents can listen to the voices of the visitors from the speaker R2.
一方、住人の音声はマイクＭ２からピックアップされ音
声信号として送話増幅回路Ｅ２へ出力される。送話増幅
回路Ｅ２からの増幅された音声信号は、略６ＭＨｚの周
波数で音声信号を変調する変調回路Ｆ２で変調され電線
路接続端子Ｔ、へ出力される。On the other hand, the resident's voice is picked up from the microphone M2 and output as a voice signal to the transmission amplification circuit E2. The amplified audio signal from the transmission amplifier circuit E2 is modulated by a modulation circuit F2 that modulates the audio signal at a frequency of approximately 6 MHz, and is output to the electric line connection terminal T.
従って、電線路ＷＩを介して接続されたドアホン子器ｌ
の電線路接続端子Ｔ、には、略６Ｍ１（ｚの周波数で音
声信号を変調する変調回路Ｆ２で変調された変調信号が
入力され、帯域フィルタ回路Ｃ７の入力となる。帯域フ
ィルタ回路Ｃ１は略６ＭＨｚを中心周波数としているの
で、帯域フィルタ回路Ｃ１は親機装置２のマイクＭ２か
らピックアップされた住人の音声信号を変調した変調回
路Ｆ２の出力のみ弁別して復調回路Ｂ１に出力する。復
調回路Ｂ、はａ機装置２のマイクＭ２からピックアップ
された住人の音声信号に復調して受話増幅回路Ａ、に出
力し、受話増幅回路Ａ、はスピーカＲ＋を駆動する。こ
のようにして、来訪者はスピーカーＲ１から住人の音声
を聴くことができる以上のようにして、来訪者と住人が
通話できるのである。Therefore, the intercom slave l connected via the electric line WI
A modulation signal modulated by a modulation circuit F2 that modulates an audio signal at a frequency of approximately 6M1 (z) is input to the electric line connection terminal T, and is input to a bandpass filter circuit C7.The bandpass filter circuit C1 is approximately Since the center frequency is 6 MHz, the bandpass filter circuit C1 discriminates only the output of the modulation circuit F2 that modulated the resident's voice signal picked up from the microphone M2 of the base device 2, and outputs it to the demodulation circuit B1. demodulates the resident's voice signal picked up from the microphone M2 of device A 2 and outputs it to the receiver amplifier circuit A, which drives the speaker R+.In this way, the visitor can listen to the speaker Visitors and residents can talk on the phone in the same way that residents' voices can be heard from R1.
ところで、ドアホン子器１のスピーカーＲ，から出力さ
れる住人の音声はマイクＭ１からピックアップされてし
まい、前述の来訪者の音声と同様の経路を通じて住人の
音声は親機装置２のスピーカーＲ２から出力される。そ
の親機装置２のスピーカーＲ２から出力された住人の音
声はマイクＭ２からピックアップされてしまい、前述の
住人の音声と同様の経路を通じて再びドアホン子器１の
スピーカーＲ５から出力される。このハウリングループ
によってハウリングが生し、双方のスピーカーＲ，，Ｒ
，からハウリング音が発生し、来訪者と住人との間の通
話が妨害されることがある。By the way, the resident's voice output from the speaker R of the door intercom slave unit 1 is picked up by the microphone M1, and the resident's voice is output from the speaker R2 of the base unit 2 through the same route as the visitor's voice described above. be done. The voice of the resident outputted from the speaker R2 of the base device 2 is picked up by the microphone M2, and is again outputted from the speaker R5 of the door intercom slave unit 1 through the same route as the voice of the resident described above. This howling loop causes howling, and both speakers R,,R
, a howling sound may be generated, which may interfere with calls between visitors and residents.
ドアホン子器１では、マイクＭ１とスピーカーＲ，との
間に遮音材の隔壁を設けたり、スピーカーＲ，の取り付
けに際してゴム座を介す等して前記ループを断ち切るよ
うに構造的に配慮しているが、完全なハウリング対策に
は到っておらず、ノλウリング音が発生して、来訪者と
住人との間の通話が妨害されることがあると言う問題点
があった本発明は、上記の問題点を改善するために成さ
れたもので、その目的とするところは、ハウリングが生
じ難く来訪者と住人との間の通話が明瞭に行えるドアホ
ン子器を提供する事にある。In the door intercom slave unit 1, structural consideration is taken to break the loop by providing a partition wall made of sound insulating material between the microphone M1 and the speaker R, and using a rubber seat when installing the speaker R. However, this invention does not provide a complete countermeasure against howling, and has the problem that a howling sound may be generated and may interfere with communication between visitors and residents. , was developed in order to improve the above-mentioned problems, and its purpose is to provide a door intercom slave unit that does not easily cause howling and allows clear communication between visitors and residents.
［課題を解決するための手段］
本発明は上記の問題点を解決するため、一対の電線路を
介して接続された親機装置との相互間で通話のできるド
アホン子器であって、ドアホン子器は少なくとも、送話
器と該送話器からの音声信号を増幅する送話増幅回路と
該送話増幅回路からの出力を変調する変調回路とより成
る送話部と、受話器と該受話器を駆動する受話増幅回路
と該受話増幅回路へ復調された音声信号を出力する復調
回路と該復調回路へ必要な周波数帯域のみ弁別して出力
する帯域フィルタ回路とより成る受話部とで構成され、
前記送話増幅回路に該送話増幅回路の増幅率を制御する
増幅率制御入力部を設けると共に、前記復調回路からの
出力に応じて出力をするレベル検知回路を設け、該レベ
ル検知回路の出力を前記増幅率制御人力部へ接続し、前
記受話器からの音声出力が大きいとき前記増幅率を絞る
ことを特徴とする。[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a door intercom slave device that can communicate with a master device connected via a pair of electric lines, The slave unit includes at least a transmitting unit including a transmitter, a transmitting amplifier circuit that amplifies the audio signal from the transmitter, and a modulation circuit that modulates the output from the transmitting amplifier circuit, a receiver, and the receiver. a receiver unit comprising a receiver amplifier circuit that drives the receiver amplifier circuit, a demodulator circuit that outputs the demodulated audio signal to the receiver amplifier circuit, and a bandpass filter circuit that discriminates and outputs only the necessary frequency band to the demodulator circuit,
The transmitting amplifier circuit is provided with an amplification factor control input section that controls the amplification factor of the transmitting amplifier circuit, and a level detecting circuit that outputs an output according to the output from the demodulating circuit, the output of the level detecting circuit being is connected to the amplification factor control manual section, and the amplification factor is reduced when the voice output from the receiver is large.
〔作用］
上記のように構成したことにより、ドアホン子器の受話
器から大きな音声が出力するとき、つまり復調回路から
の出力が大きいとき、レベル検知回路が復調回路からの
出力が大きいことを検知し゛て増幅率制御入力部に制御
出力するので、送話増幅回路の増幅率は絞られる。そこ
で、送話器からの音声信号は絞られて変調回路に入力さ
れ、ハウリングしないのである。[Function] With the above configuration, when a loud voice is output from the handset of the door intercom handset, that is, when the output from the demodulation circuit is large, the level detection circuit detects that the output from the demodulation circuit is large. Since the signal is controlled and output to the amplification factor control input section, the amplification factor of the transmitting amplification circuit is narrowed down. Therefore, the audio signal from the transmitter is narrowed down and input to the modulation circuit to prevent howling.
以下、本発明の一実施例を第１図に基づいて説明する。 Hereinafter, one embodiment of the present invention will be described based on FIG.
第１図は、本発明に係るドアホン子器１の通話回路の要
部を示す回路ブロック図であり、従来例と異なる構成は
次の点である。FIG. 1 is a circuit block diagram showing the main parts of a telephone call circuit of a door intercom slave unit 1 according to the present invention, and the configuration differs from the conventional example in the following points.
つまり、送話増幅回路Ｅ、に自分自身の増幅率を制御す
る増幅率制御入力部４を設けたこと、及び、復調回路Ｂ
１の出力に応じた出力をするレベル検知回路Ｄ１を設け
たこと、並びに、復調回路Ｂ１の出力をレベル検知回路
ＤＩに接続すると共にレベル検知回路り、の出力を増幅
率制御入力部４に接続することによって、ドアホン子器
ｌのスピーカーＲ１から住人の大きな音声が出力すると
き、送話増幅回路Ｅ、の増幅率は絞られることである。That is, the transmitting amplifier circuit E is provided with the amplification factor control input section 4 that controls its own amplification factor, and the demodulating circuit B
In addition, the output of the demodulation circuit B1 is connected to the level detection circuit DI, and the output of the level detection circuit DI is connected to the amplification factor control input section 4. By doing so, when the resident's loud voice is output from the speaker R1 of the door intercom slave l, the amplification factor of the transmitting amplifier circuit E is reduced.
従って、住人の大きな音声がドアポン子器１のスピーカ
ーＲ１から出力されると共に、スピーカーＲ，から出力
された住人の音声がマイクＭ、に入力されても、このと
き送話増幅回路Ｅ、の増幅率は絞られているので、親機
装置２のスピーカーＲ２から出力される住人の音声は小
さいものとなり、再び、その住人の音声が親機装置２の
マイクＭ２からピックアップされることがなくなる。よ
って、従来の技術で説明したようなハウリングループが
ここで断ち切られハウリングの発生が防止されることに
なる。Therefore, even if the resident's loud voice is output from the speaker R1 of the doorbell unit 1, and the resident's voice output from the speaker R is input to the microphone M, at this time, the transmitting amplifier circuit E is amplified. Since the ratio is narrowed down, the voice of the resident output from the speaker R2 of the base device 2 becomes small, and the voice of the resident will not be picked up from the microphone M2 of the base device 2 again. Therefore, the howling loop as described in the related art is cut off here, and the occurrence of howling is prevented.
なお、住人が親機装置２から来訪者に話しかけると同時
に来訪者がドアホン子器１から住人に話しかけると、こ
の時来訪者の音声が親機装置２のスピーカーＲ２からは
小さな音量でしか聴こえないことになる。しかし、この
ようなことは頻繁には起こらないので使用上支障とはな
らない。Note that if the resident speaks to the visitor from the base device 2 and the visitor speaks to the resident from the doorbell slave 1 at the same time, the visitor's voice will only be heard at a low volume from the speaker R2 of the base device 2. It turns out. However, since this does not occur frequently, it does not pose a problem in use.
なお、同様の増幅率制御入力部及びレベル検知回路を親
機装置２側に設けても同様の効果があることは言うまで
もない。It goes without saying that a similar effect can be obtained even if a similar amplification factor control input section and level detection circuit are provided on the base device 2 side.
本発明のドアホン子器は上記のように構成されているの
で、ハウリングが発生し難くなり、ドアホン子器と親機
装置との間の来訪者と住人の通話が明瞭に行えるドアホ
ン子器を提供できると言う効果を奏する。Since the door intercom slave device of the present invention is configured as described above, howling is less likely to occur, and a door intercom slave device is provided that allows clear communication between visitors and residents between the door intercom slave device and the base device. It has the effect of saying it can be done.
第１図は本発明に係るドアポン子器の一実施例を示す通
話回路の要部を示す回路ブロック図、第２図は従来のド
アホン子器及び親機装置の通話回路の要部を示す回路ブ
ロック図、第３図はドアホン子器及び親機装置の正面図
である。
１− ドアホン子器、２−親機装置、４−増幅率制御入
力部、Ａ＝−受話増幅回路、貼−復調回路、Ｃ１−帯域
フィルタ回路、Ｄ、−レベル検知回路、Ｅｌ ・−送話
増幅回路、Ｆｌ−変調回路、Ｍｌ−送話器、Ｒ１−受話
器、Ｗ、、Ｗ２−電線路特許出願人 松下電工株式会
社FIG. 1 is a circuit block diagram showing the main parts of the call circuit of an embodiment of the doorbell slave device according to the present invention, and FIG. 2 is a circuit diagram showing the main parts of the call circuit of the conventional doorbell slave device and base device. The block diagram and FIG. 3 are front views of the door intercom slave device and the base unit device. 1- door intercom slave device, 2- main unit device, 4- amplification factor control input section, A = - receiving amplifier circuit, pasting - demodulating circuit, C1 - bandpass filter circuit, D, - level detection circuit, El - transmitting call Amplifier circuit, Fl-modulation circuit, Ml-transmitter, R1-receiver, W,, W2-electric line patent applicant Matsushita Electric Works Co., Ltd.
Claims (1)
互間で通話のできるドアホン子器であって、ドアホン子
器は少なくとも、送話器と該送話器からの音声信号を増
幅する送話増幅回路と該送話増幅回路からの出力を変調
する変調回路とより成る送話部と、受話器と該受話器を
駆動する受話増幅回路と該受話増幅回路へ復調された音
声信号を出力する復調回路と該復調回路へ必要な周波数
帯域のみ弁別して出力する帯域フィルタ回路とより成る
受話部とで構成され、前記送話増幅回路に該送話増幅回
路の増幅率を制御する増幅率制御入力部を設けると共に
、前記復調回路からの出力に応じて出力をするレベル検
知回路を設け、該レベル検知回路の出力を前記増幅率制
御入力部へ接続し、前記受話器からの音声出力が大きい
とき前記増幅率を絞ることを特徴とするドアホン子器。(1) A door intercom slave unit that is capable of communicating with a base unit connected via a pair of electrical lines, and the door intercom slave unit at least communicates with a transmitter and an audio signal from the transmitter. a transmitting section comprising a transmitting amplifier circuit for amplifying and a modulation circuit modulating the output from the transmitting amplifier circuit, a receiver, a receiving amplifier circuit for driving the receiver, and a demodulated audio signal to the receiving amplifier circuit; It is composed of a demodulation circuit that outputs an output, and a band filter circuit that discriminates and outputs only a necessary frequency band to the demodulation circuit. A control input section is provided, and a level detection circuit is provided that outputs an output according to the output from the demodulation circuit, and the output of the level detection circuit is connected to the amplification factor control input section, so that the audio output from the receiver is large. A door intercom slave device characterized in that the amplification factor is narrowed down when the amplification factor is reduced.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25999190A JPH04135355A (en) | 1990-09-27 | 1990-09-27 | Doorphone slave unit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25999190A JPH04135355A (en) | 1990-09-27 | 1990-09-27 | Doorphone slave unit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH04135355A true JPH04135355A (en) | 1992-05-08 |
Family
ID=17341772
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP25999190A Pending JPH04135355A (en) | 1990-09-27 | 1990-09-27 | Doorphone slave unit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH04135355A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8019269B2 (en) | 2007-03-23 | 2011-09-13 | Brother Kogyo Kabushiki Kaisha | Image forming apparatus |
-
1990
- 1990-09-27 JP JP25999190A patent/JPH04135355A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8019269B2 (en) | 2007-03-23 | 2011-09-13 | Brother Kogyo Kabushiki Kaisha | Image forming apparatus |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP4483134B2 (en) | Loudspeaker call system | |
| JPH04135355A (en) | Doorphone slave unit | |
| JPH0533094Y2 (en) | ||
| JP2980963B2 (en) | Door phone cord | |
| JP3673935B2 (en) | Intercom system | |
| JP4161643B2 (en) | Intercom system | |
| JPS63187845A (en) | Radiotelephony equipment | |
| JP2002057803A (en) | Loudspeaker system | |
| JP3034658U (en) | Phone volume control | |
| JP2000151821A (en) | Interphone system | |
| JP2002261945A (en) | Interphone device | |
| JP2533760Y2 (en) | Intercom master unit having monitor function and intercom system using the same | |
| JPH03262239A (en) | Cordless telephone system | |
| JP2004207855A (en) | Interphone system | |
| JP3040531B2 (en) | Intercom equipment | |
| JP3428880B2 (en) | Intercom equipment | |
| JPS602705Y2 (en) | public address telephone | |
| JPH10326396A (en) | Security interphone device | |
| JPS61201555A (en) | Electronic key telephone set | |
| JPS6167357A (en) | Hand free telephone set | |
| KR970056685A (en) | Wireless intercom | |
| JP2000287198A (en) | Video doorphone system | |
| GB2218302A (en) | Hands-free telephone | |
| JPH08107463A (en) | Terminal equipment for magnet type telephone line | |
| JPH08181766A (en) | Loudspeaking equipment |